The field of the invention is waste paper processing machinery and the invention relates more specifically to a process for making pulp from used corrugated containers and other grades of waste paper. With the increased interest in conservation of natural resources and particularly forests, there has been an increased interest in recycling waste paper and waste corrugated containers. Such waste containers provide an important resource and by the proper technique may be broken down in water to a pulp which may be used as a portion or entirely as a source of pulp for additional processing into useful paper products.
In the past, the most common method of defibrilating waste paper has been to place it in a tank of water which has an agitator blade at the bottom or at the sides of the tank. The soaking action of the water combined with the agitator action of the blade tends to break up the paper or cardboard into its original fibers which can then be removed from the tank. One such process is shown in U.S. Pat. No. 4,129,259 to Vokes. The major problem, however, with this type of process is the difficulties caused by foreign matter such as string or wire which become tangled in the impeller and must be manually or mechanically removed periodically which is both time consuming and difficult. This process also breaks up glass and other brittle materials into tiny particles which must be removed in a centrifuging or other separating process. Other machines which have been used for this purpose are shown in the following U.S. Pat. Nos: 3,941,316, 4,163,036, 1,831,642, 2,917,245, and 3,993,252. All of the above shown apparatuses suffer from various defects and most of them are inefficient users of either water or electricity or both and a more efficient process which is capable of recycling its water is needed to maximize the efficiency of this recycling process.